That's a reasonable thing to ask. How "nerdy" he is often depends on the adaptation. Sometimes it looks like he extremely enjoys being a scientist. Other times, it looks like he's only coasting on his natural talents. If he were naturally strong, he might've become a pro wrestler or soldier.
It would explain why he doesn't seem particularly motivated to continue his coursework.
Another excuse is that after having most of his scientist jobs sabotaged by something, he's lost hope that he'll be a legit scientist and has subconsciously given up.